My Tunze Osmaolator Automated Water Change

this is cool. any trouble with evaporation from your SW reservoir? how do you keep the reservoir mixed & aerated?

 

I don't really worry about that. I could make my own, but I don't really have space and I can't plumb it into my equipment closet. So I got to the LFS for my water. It is only a 7g jug and I'm only changing 1g at a time, so I don't really worry about aeration. Guess I coulds shake the jug from time to time. Guess I should start checking if anything is settling out.

 

Well just an update... this setup has been working flawlessly. One of the best mods I've done.

The controller is set to pump out so much then stop and let the ATO catch up. Probably no need for that but I have the ability so I do it.

This setup could change out about 2-3 gallons at a time... depending on head... you would actually have to measure it out. Run the pump for 8 minutes to see how much it would replace. I am only doing one change a day.... but for bigger tanks you could do multiple changes. Course you would need much bigger resivoirs.

For my little set up... the one gallon a day is perfect. A jug lasts me one week. The waste jug I dump every 4-5 days. All I have to do is swap out bottle and my water changes are done. I actually don't see why more people do do this. Virtually any ATO could be made to perform the same. But this way my ATO and auto water change only take up two plugs on my controller strip. If you are on the fence about an ATO... get the Osmolater and add this mod and you are set.

 

I love it.

 

So the problem with using an ATO is that the sump will not be 100% topped off at the beginning of a water change 100% of the time. So if it is half way in between, when the water change cycles, it will top off to high level, and make up a bit of salt water. Over time this will creep up salinity a bit.

My salinity got a little low.... then I had to raise MG, so I wanted to raise my salinity a bit. Point is I have not seen any creep up. With a Tunze Osmolator, in my return section... you are talking maybe a couple of ounces of salt water a day. Plus with me dosing 2 part, my salinity will creep up over time any way.

So to combat this... all I have to do is get rid of some water manually and let the RO/DI make up when ever I feel like it. Certainly no big deal. What... maybe a gallon or two a month???

One thing I just thought of though is that when power is cut to the Osmolator and restored, the ATO will kick in for 10 sec to assure it is working right. All I would have to do is just cycle power to my Osmolator prior to starting the water change. That way the sump is always topped off or over full getting rid of some salt water. I have not found a need for this yet, but I might do it in the future depending on how things go. Just another great feature I realized.

Now the "CADILAC" version of this would be to get a conductivity probe and module for my Apex. That would cost me $200. However... I would never have to worry about salinity any more. My ATO would run, my continuous water change would cycle, and the conductivity probe could control it all by switching the relay between RO/DI and saltwater for top off to keep conductivity is a narrow range. 100% automation.

 

So this question came up in another thread, butI wanted to add some info to this thread....

So then if I understand you John... you have your RO hooked up directly to the tank, and when you need to top off, you have your controller open a selenoid valve to put water through the RO. Is that correct?

Having a fresh water source directly hooked up to your tank is not a good idea... but that is a different discussion and I know you have heard it.

So here is the point John... to do a automated water change, you have to put back as much as you took out. A couple of expensive ways to accomplish that, but a very easy and cheap way to do it with an ATO.

You have to have your controller switch from using your ATO to top off with fresh water, to have it top off with salt water. What ever you pump out to waste, will be topped off with your ATO float switches switched to salt water. All that takes is a $15 DPDT relay from Radio Shack.

You start all this by turning off your ATO. How ever you turn it on, just turn it off so it won't top off when the water goes low.

So you need a cheap stupid pump. Anything. Controller turns on waste pump for so much time... gets rid of so much water from your sump. Now you are low.

So you tell your controller to energize (turn on) your relay because it is a 120vac relay that is plugged into your power strip. What is wired to the relay is your ATO selenoid for your RO, and to a NEW pump you added to pump NEW salt water back in. So when it is off, your RO selenoid is on, and when it is on, your salt water pump is on.

Then... I assume you have your ATO float switches controlled by your controller... you tell your controller to turn off your salt water pump when "float 1 = on" or however you have it set up.

At that point you are topped back off to where you started and you have changed out so much salt water.

You then tell your controller to "turn off" your relay, and now power is restored to your RO selenoid and will continue to function and top off fresh water like it always did.

So the Key is to use a relay to switch between topping off with fresh water and salt water. Another simple and cheap pump for your salt water, and another simple and cheap pump to pump out waste water.

You CAN'T set up a siphon with your waste water.
Your waste pump will not "stick" on.
You can use a float to trigger a stop everything.
You can program in all the safety you want
You will not change anything on your ATO or it's reliability
You can do this once a day or several times a day.
All it takes is a quick glance at your jugs to see what happened that day and start building trust.


This definitely needs some discussion, because it is possible I am not applying something right trying to do it with floats, and not my Tunze

 

Ok... I included a diagram to help everyone understand what I currently have.

I am needing to add in a 2 pumps. One to pump out the old water, then add the new water in.

If I am looking correctly, I should be able to use the lower float, and hook that to the Apex as well.

Apex turns OFF power to ATO
Apex turns ON discharge pump for 1 minute.
Apex turns ON new water pump, until lower float is reached.
Cycle every 24Hhrs

Do you think this will work?

 

That does help John... it's even simpler. So... you have a brain box that runs your ATO. Your float switches activate the brain, and the brain puts out an output to your selenoids.

All you need to do is switch the output from your brain from your fresh water selenoids, to a salt water source.

So it your out put from your brain is 120vac... then that is easy. The relay takes in 120 and switches it from the selenoids to a pump at 120.

If your brain output is some low voltage DC... then to keep from using multiple relays or other stuff... the way you have would work fine.

16:00 You would just turn off your ATO.
16:01 turn on waste pump 90 sec
16:03 turn on salt water pump
If float 1 = on then salt pump off
16:05 turn off salt pump
16:06 turn on ATO

You just work out your system and know how long everything shoul dtake. How long for how much you want to get rid of. How long for what you need to put back.... then if a float fails then just a little after when it should be topped off turn it off anyway for added safety. If you have a wet floor switch then tell Apex to keep it all off.

Not sure why you have 4 selenoids. I assume for redundant offs. If you did away with the brain box, Apex is robust enough to just be your ATO with float switches. All I'm saying is then you could add safety statemements like never turn on the selenoids for more than 1 minute... otr something like that because if it was topping off for 5 minutes something is definitely wrong

Not that your ATO is not working great, but that there is more safety code you could add if Apex was running the show.

 

Still confused about how to switch the 120 output from solenoids to the pump.

 

I did this too! It's really great! Just time it to make sure you don't hit the alar. I have mine go off 3 times a day for about 2 gallons total a day. Thanks for turning me onto this great diy Powerman!